Communication device and method for efficiently receiving MIMO signals

Abstract

Communication device adapted for receiving a MIMO signal is provided. The device comprises a first detector adapted to perform a first symbol detection on the MIMO signal using a first detection method, a detection error determination unit adapted to determine a first detection error of the first symbol detection, a detection error judging unit adapted to determine if the first detection error is above or below a detection threshold, and a second detector, adapted to perform a second symbol detection on the MIMO signal using a second detection method, if the detection error judging unit has determined that the first detection error is above the detection threshold. The communication device is adapted to use results of the symbol detection as final symbol detection results, if the detection error judging unit has determined that the first detection error is below the detection threshold.

What is claimed is: 
     
       1. A communication device adapted for receiving a multiple-input and multiple-output (MIMO) signal, the device comprising:
 a first detector adapted to perform a first symbol detection on the MIMO signal using a first detection method, 
 one or more processors adapted to determine if a first detection error of the first symbol detection is below or above a detection threshold, 
 a second detector adapted to perform a second symbol detection on the MIMO signal using a second detection method, when the first detection error is determined to be above the detection threshold, 
 the one or more processors is further adapted to determine if a second detection error of the second symbol detection is below or above the detection threshold, and
 wherein the communication device is adapted to use results of the first symbol detection as final symbol detection results when the first detection error is determined to be below the detection threshold and the communication device is adapted to use results of the second symbol detection as the final symbol detection results when the second detection error is determined to be below the detection threshold. 
 
 
     
     
       2. The communication device according to  claim 1 , wherein the second symbol detection is an iterative symbol detection method,
 wherein the one or more processors is further adapted to determine the second detection error after each iteration, and determine if the second detection error is below or above the detection threshold after each iteration, 
 wherein the second detector is adapted to perform a further iteration, when the second detection error is determined to be above the detection threshold, and
 wherein the communication device is adapted to use results of the second symbol detection as final symbol detection results, when the second detection error is determined to be below the detection threshold. 
 
 
     
     
       3. The communication device according to  claim 1 , wherein the first detection method comprises a lower detection accuracy and a lower computational complexity than the second detection method. 
     
     
       4. The communication device according to  claim 1 ,
 wherein the first detection method is a minimum mean square error (MMSE) detection method or a zero-forcing (ZF) method, and 
 wherein the second detection method is a successive interference cancellation (SIC) method or a sphere decoder (SD) method or a maximum likelihood (ML) method. 
 
     
     
       5. The communication device according to  claim 1 , comprising a third detector adapted to perform a third symbol detection on the MIMO signal using a third detection method, when the second detection error is determined to be above the detection threshold, and
 wherein the communication device is adapted to use results of the third symbol detection independent of a third detection error of the third symbol detection. 
 
     
     
       6. The communication device according to  claim 5 ,
 wherein the first detection method comprises a lower detection accuracy and a lower computational complexity than the second detection method, and 
 wherein the second detection method comprises a lower detection accuracy and a lower computational complexity than the third detection method. 
 
     
     
       7. The communication device according to  claim 6 ,
 wherein the first detection method is a minimum mean square error (MMSE) detection method or a zero-forcing (ZF) method, 
 wherein the second detection method is a successive interference cancellation (SIC) method or a sphere decoder (SD) method, and 
 wherein the third detection method is a maximum likelihood (ML) method. 
 
     
     
       8. The communication device according to  claim 1 , wherein the one or more processors is further adapted to determine the detection threshold adaptively. 
     
     
       9. The communication device according to  claim 1 ,
 wherein the one or more processors is further adapted to determine one or more of the following:
 a) the detection threshold adaptively dependent upon a signal-to-noise-ratio of the MIMO signal, 
 b) a battery level of a battery of the communication device, 
 c) a temperature of the communication device, and/or an availability of computational resources, and/or an accuracy of available channel state information of the MIMO signal. 
 
 
     
     
       10. The communication device according to  claim 1 ,
 wherein the one or more processors is further adapted to determine the detection threshold as a higher value for a lower signal-to-noise-ratio, a lower battery level of the battery of the communication device, a higher temperature of the communication device, a lower availability of computational resources, and a lower accuracy of available channel state information of the MIMO signal, and 
 wherein the one or more processors is still further adapted to determine the detection threshold as a lower value for a higher signal-to-noise-ratio, a higher battery level of the battery of the communication device, a lower temperature of the communication device, a higher availability of computational resources, and a higher accuracy of the available channel state information of the MIMO signal. 
 
     
     
       11. The communication device according to  claim 8 , wherein the one or more processors is further adapted to determine the detection threshold through the following:
     t=NRx*σ   2 +ε
 
 wherein t is the detection threshold, 
 wherein NRx is a number of receiver antennas receiving the MIMO signal, 
 wherein σ 2  is the variance of the noise of the transmission channel of the MIMO signal, 
 wherein ε is a detection tolerance parameter adjusting the detection threshold. 
 
     
     
       12. The communication device according to  claim 1 ,
 wherein the one or more processors is further adapted to determine the detection errors through the following:
     d=∥H* x −y∥   2   2    
 
 wherein d is a scalar representing a sufficient statistic for the received vector y, 
 wherein H is an effective channel matrix of a transmission channel of the MIMO signal, 
 where  x  is a vector of the detection results. 
 
     
     
       13. A reception method for receiving a multiple-input and multiple-output (MIMO) signal, the method comprising:
 performing a first symbol detection on the MIMO signal using a first detection method, 
 determining if a first detection error of the first symbol detection is below or above a detection threshold, 
 performing a second symbol detection on the MIMO signal using a second detection method, when it has been determined that the first detection error is above the detection threshold, 
 determining if a second detection error of the second symbol detection is below or above the detection threshold, 
 using results of the first symbol detection as final symbol detection results when the first detection error is below the detection threshold; and 
 using results of the second symbol detection as the final symbol detection results when the second detection error is below the detection threshold. 
 
     
     
       14. The method according to  claim 13 , wherein the second symbol detection is an iterative symbol detection method, and the method further comprises:
 determining the second detection error after each iteration, 
 determining if the second detection error is below or above the detection threshold after each iteration, 
 performing a further iteration, when it has determined that the second detection error is above the detection threshold, and 
 using results of the second symbol detection as final symbol detection results, when it has determined that the second detection error is below the detection threshold. 
 
     
     
       15. The method according to  claim 13 , wherein the first detection method comprises a lower detection accuracy and a lower computational complexity than the second detection method. 
     
     
       16. The method according to  claim 13 , wherein the first detection method is a minimum mean square error (MMSE) detection method or a zero-forcing (ZF) method, and
 wherein the second detection method is a successive interference cancellation (SIC) method or a sphere decoder (SD) method or a maximum likelihood (ML) method. 
 
     
     
       17. A non-transitory computer readable medium, comprising processor-executable instructions stored thereon, which when executed by a hardware processor cause the processor to implement operations including:
 performing a first symbol detection on the MIMO signal using a first detection method, 
 determining if a first detection error of the first symbol detection is below or above a detection threshold, 
 performing a second symbol detection on the MIMO signal using a second detection method, when it has been determined that the first detection error is above the detection threshold, 
 determining if a second detection error of the second symbol detection is below or above the detection threshold, 
 using results of the first symbol detection as final symbol detection results when the first detection error is below the detection threshold; and 
 using results of the second symbol detection as final symbol detection results when the second detection error is below the detection threshold. 
 
     
     
       18. The computer readable medium according to  claim 17 , wherein the operations further include:
 determining a second detection error of the second symbol detection, 
 determining if the second detection error is below or above the detection threshold, and 
 using results of the second symbol detection as final symbol detection results, when it has determined that the second detection error is below the detection threshold.